This invention relates to safety spectacles in general and particularly concerns an improved plastic frame for such spectacles wherein the lenses are securely retained in accordance with accepted safety standards yet may be removed and replaced using only manual pressure and without the need for special processing techniques.
Safety spectacles have long been used in industrial environments to protect workers from serious eye injuries. With the recent enactment of comprehensive federal legislation regarding safe working environment, use of safety spectacles has significantly increased.
It will be appreciated that the provision of safety glasses for workers amounts to a considerable expense which must be born in every case by the employer. In the interest of alleviating this financial burden somewhat, relatively inexpensive plastic frame safety glasses have met with wide acceptance.
A problem with safety spectacles in general, and plastic frame glasses in particular, is that the lenses frequently become severely pitted or scratched after only a short period of use due to the oftentimes severe environment to which the safety glasses are subjected. In addition to impairing visibility, such pitting and scattering may weaken the lens to the point where it is no longer able to meet impact requirements set for safety-type lenses. Hence, continued use of safety spectacles having worn lenses may be detrimental to the safety of the worker in addition to being annoying from the standpoint of reduced vision.
Again in the interest of reduced expenses, it is common practice to replace worn lenses in plastic frame safety spectacles as necessary rather than simply discarding the entire spectacle. However, heretofore lens replacement has proved particularly difficult and in some instances the frames are returned to the manufacturer for replacement of the lenses. This for the reason that plastic frames should be heated in order to install new lenses and special care must be taken to assure that the new lenses are properly seated to provide a safe spectacle. In this latter regard, improper installation of safety lenses by unskilled personnel may result in a lens which is subject to being dislodged upon impact such that the wearer is not adequately protected by the safety spectacle.
Replacement of safety spectacle lenses has proved troublesome and expensive for employers who provide safety glasses to their employees. Of course the fact that skilled labor is required to replace the lenses is in itself a significant factor in the expense of maintaining safety spectacles. Moreover, in instances where the employer returns the safety glasses to the factory for lens replacement, he must necessarily have an additional supply of safety spectacles to be used during times when others are at the factory for lens replacement.